Abstract
The [19.20]0<sup>+</sup>-X<sup>1</sup>Σ<sup>+</sup> (0,0) band system of gold chloride, AuCl, has been studied using optical Stark spectroscopy. The [19.20]0 state is analysed as a <sup>3</sup> electronic state, and the observed Stark shifts analysed to determine ground and excited electronic state permanent electric dipole moments, el. A considerably smaller <inf>el</inf> of 0.32 ± 0.17 D for the [19.20]0<sup>+</sup> (v = 0) state, in comparison to that of 3.69 ± 0.02D for the X<sup>1</sup>Σ<sup>+</sup> (v = 0) state is observed. The experimental assignment of the [19.20]0<sup>+</sup> state to a component of the <sup>3</sup>Π state has been corroborated by high-level quantum-chemical calculations using exact two-component theory for treating relativistic effects and the equation-of-motion coupled-cluster approach for describing the electronic excited state. A close inspection of the electronic wave functions for the <sup>3</sup>Π states of gold monohalides reveals significant participation of excitations from the halogen valence p orbitals to the anti-bonding molecular orbitals mainly localised on the gold atom. This leads to a charge transfer from halogen to gold and is responsible for the dramatic reduction of dipole moment in the <sup>3</sup>Π states in comparison to the ground states as observed in the Stark-shift analysis. It has been further demonstrated that this ligand to metal charge transfer increases along the F to I series and leads to predicted dipole moments in the <sup>3</sup>Π states of AuBr and AuI that point towards the gold atoms, qualitatively different than might be anticipated.
Original language | English (US) |
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Pages (from-to) | 2073-2080 |
Number of pages | 8 |
Journal | Molecular Physics |
Volume | 113 |
Issue number | 15-16 |
DOIs | |
State | Published - Aug 18 2015 |
Keywords
- equation-of-motion coupled-cluster
- gold chloride
- optical Stark spectroscopy
- permanent electric dipole moments
- quantum-chemical calculations
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Condensed Matter Physics
- Biophysics
- Molecular Biology